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Maps

There are several sources of base maps that are suitable for use with our programs:

• Base maps compiled by the Adit team



• Maps compiled by AditSite users



• Maps derived from DMAP files (contact DMAP for copyright issues)



• Map tiles downloaded from the web (Ordnance Survey, Multimap, etc. or loaded from CD)



• Outline files downloaded from the web (Ordnance Survey, English Nature, Etc.)



• Digitised Watsonian Vice-Counties of Great Britain and derived maps (contact NBN for copyright issues)

Please note, these base maps are copyright-free for private use only. You must contact the owner (e.g. Adit, AditSite user, DMAP, Ordnance Survey, MultiMap, English Nature, NBN etc) if you wish to use these maps commercially.

If in doubt, contact Adit direct.

If you have any maps that you are happy to share with others, please email them to us.

If you need a map, and cannot find it here, we may be able to get hold of something for you - it's always worth asking.
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Help with building maps

Adit has the expertise to advise you about your requirements or we can build the map for you.

Contact the Adit team whatever your need with mapping.

Depending on the nature of the enquiry, we may be obliged to pass on a small charge, if you request us to undertake work for you.
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Sample maps available for use with AditSite and AditMap

• The following maps are available for users of AditSite and AditMap, as a starting point for creating your own maps, and include maps of vice-county boundaries



• Some of these maps are very good, others are simple outlines but they can be a good place to start. Thanks are due to users who have made contributions



• For each collection, click on the link which will take you to a zip file, where you can select the AMF file for your chosen area
  
  
  
  • A collection of UK Boundary Maps
  
  
  • English counties and other maps of England
  
  
  • Welsh counties and other maps of Wales
  
  
  • Scottish counties and other maps of Scotland
  
  
  • Ireland maps

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Adit guide to maps, mapping and cartography by Mike Griffiths

A dictionary definition might go like this:
“A diagrammatic representation of the earth's surface, or part of it, showing the geographical distributions and positions of features such as roads, towns, rainfall, etc.”

I am going to stick my neck out and define a map as a diagram which includes information about location, orientation and scale.

• Location because it is important to know where the map represents



• Orientation and scale so that we could use the map to navigate ourselves around its features or to determine the relationship between the features portrayed.

This definition might include architectural plans for a new building, simple “how to find us” sketches as well as the highly detailed maps produced by national survey organisations.

It has to be noted that this tighter definition would fail to include one of the most famous maps in the world:

The London Underground (Tube) system map

• This map was originally designed by Harry Beck and has been rightly heralded as a design triumph



• It clearly communicates directions to the transport system users and yet happily distorts both location and scale



• The design concept has been copied by other city transport systems around the world



• See Transport for London for more information



• Perhaps we should therefore introduce the concept of Purpose or Communication to our map definition and require the map designer to come up with the best definition for the subject



• A map has a purpose which will tend to distort the representation



• For instance, a road map has a specific purpose - to show a selection of roads, their general path and the junctions between them. The lines used to represent these roads have a width that does not obey the scale of the map. We have grown used to the convention that map features are not drawn to the overall scale of the map (although in most instances their relative position does conform to the scale).

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Map Distortions

Most people in the Western world would readily recognise the coastal outline of the United States or of the United Kingdom. We are happy to ignore the fact that these outlines are gross simplifications of the true coastal outline – even if we have given any thought to what a coastal outline actually represents. Is it the permanently dry bits, and average line between high and low tides or is it another arbitrary line?

Line simplification is a necessary function of scale – we are used to the fact that different scale maps represent features with greater and lesser degrees of detail. We could construct a new map of, say, our locality/research site and base it on our own measurements, taken from a single “datum” point or line; in effect, do our own survey and record the results in the form of a map.

In practice, we will often base a new map on an existing co-ordinate system or upon some existing and trusted reference map. Most maps and co-ordinate systems are “flat” representations of part of the surface of the Earth – a roughly global planet. The representation of a curved surface, using a flat map, has to introduce some distortion of its own. The process of mapping a curved surface onto a plane is known as creating a projection.

As well as the overall distortion introduced by a specific projection we also have to contend with the fact that (at a local level) the Earth does not have a smooth surface. It has hills, mountains and valleys. The distance you might have to trek between two mountain peaks could be very different to the scale difference between them on a map. Few printed maps are capable of representing surface distances accurately across even mildly undulating countryside. Perhaps three dimensional electronic maps will become a feature of our lives in the future but for the moment we have to rely upon our human interpretation of contour lines and other map features to judge distance over the ground.

So what are we playing at with these selective collections of distortions and simplifications we call maps? It just so happens that maps are an amazingly powerful media for transferring knowledge and information between human beings. We at Adit Limited spend a lot of time working with individuals and organisations with specific concern and responsibility for the environment. All these individuals and organisations make extensive use of maps and mapping tools such as AditMap to record, plan and report on their areas of research and stewardship.

Many people are aware of the fascination of detailed maps such as the UK Ordnance Survey Landranger series or my own local Institut Geographique National 1:25000 maps in France. These maps provide a detailed documentation of an area and even it’s history. You can take a stroll in your mind from village to ancient monument to river bank. You can learn about and visualise a place you have not yet visited, just by reading a map.
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Map Projections

There are a great many map projections. Some date back to ancient times and some are more modern. They fall into three broad groups. The cylindrical, conical and azimuthal groups. The best know of all is probably the Mercator projection which is a cylindrical projection. A few of the known projections are described and illustrated below. This is not therefore a definitive guide but simply a sample to help explain the nature and benefits of the three main types.
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The Mercator Projection

Probably the most famous of the various map projections, the Mercator projection takes its name from Mercator who presented it in 1569. It is a cylindrical, conformal projection with no distortion along the equator. A major navigational feature of the projection is that a line of constant azimuth is straight. Such a line is known to seamen as a rhumb line. Thus, to sail from one point to another one only had to connect the points with a straight line, and keep this constant course for the entire voyage. This property is also known as comformality. The Mercator projection has been used extensively for world maps. You will notice that there is a marked distortion towards the polar regions and that countries such as Greenland appear larger then they are.

A transverse mercator projection is a mercator projection rotated through 90 degrees. This projection is widely used for land masses with a North/South expanse and is the basis for the Universal Transverse Mercator (UTM) co-ordinate system.
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Conical Projections

In the Conical Projection the graticule is projected onto a cone tangent to the globe along any small circle (usually a mid-latitude parallel). In the normal aspect (which is oblique for conic projections), latitude parallels are projected as concentric arcs of circles, and longitude meridians are projected as straight lines radiating at uniform angular intervals from the apex of the flattened cone. Conic projections are best suited for maps of temperate latitudes, especially those elongated in an east/west direction. The United States meets these qualifications and therefore is frequently mapped on conic projections.

Lambert conformal conic

Developed by J.H. Lambert in 1772 but further developed by others during the 19th Century. The First World War gave this projection new life, making it the standard projection for intermediate and large-scale maps of regions in middle latitudes for which the transverse Mercator was not then used.

Azimuthal Projections

The most noticeable feature of this azimuthal projection is the fact that distances and directions measured from the centre of the map are true. Therefore, a circle about the projection centre defines the locus of points that are equally far away from the plot origin. It is a useful projection for a global view of locations at various or identical distance from a given point and this should be located at the centre of the map.

Lambert Azimuthal equal-area projection

This projection was developed by Lambert in 1772 and is typically used for mapping large regions like continents and hemispheres. It is an azimuthal, equal area projection. Distortion is zero at the centre of the projection, and increases radially away from the centre point.


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Polar Stereographic Projection

This is a conformal, azimuthal projection that dates back to the Greeks. It's main use is for mapping the polar regions. When a polar region is shown then all longitude meridians are straight lines and latitude parallels are arcs of (or complete) circles.
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Which projection is right for your map?

If minimal distortion were the only issue then the choice would be relatively straightforward:

• Cylindrical projections are best for tropical areas



• Conical projections are best for temperate areas



• Azimuthal projections would work best for polar regions



• For navigational purposes conformality is essential and this might override any other choice factor



• Distortion, resulting from the projection used, is unlikely to be evident on very large scale maps, so one might well end up using a cylindrical projection in many more instances than the simple issue of overall distortion would imply.